[75.01] The South Pole Imaging Fabry Perot Interferometer (SPIFI)

We present the completed South Pole Imaging Fabry-Perot
Interferometer (SPIFI) for use on the AST/RO telescope and
the JCMT. SPIFI is a direct-detection spectrometer for use
in the far-infrared and submillimeter windows (200, 350,
450, and 600 \mum) accessible at the South Pole and the
submillimeter windows available at Mauna Kea. The 25
element (5 x 5) bolometer array is cooled to \sim 100 mK
with an adiabatic demagnetization refrigerator, and sees a
300'' field (beam is 55'') and a 35'' field (7''
beam) on the 1.7 m AST/RO telescope and on the 15 m
JCMT, respectively. SPIFI's three cryogenic Fabry-Perot
interferometers operate in series to achieve spectral
resolutions from 300 to 30 km/sec across the entire field
of view, while much higher resolution can be achieved on
the center pixel. As a direct-detection instrument, SPIFI
is significantly more sensitive than the best heterodyne
receivers for lines well matched to its spectral
resolution. In addition, its spatial multiplexing makes
SPIFI an ideal instrument for mapping projects. We hope to
use SPIFI at the JCMT by mid-year 1997 and to deploy to the
South Pole in November 1997.

The scientific goals of SPIFI include the large-scale
mapping of the [CI] (370 \mum) and [NII] (205 \mum) fine
structure lines, and the CO 7-6 (372 \mum) rotational
transition in nearby star formation regions, the Galactic
Center, and external galaxies. These lines probe the
interaction between young stars and their molecular cloud
environs, as well as the internal structure of molecular
clouds. In addition, SPIFI on JCMT can detect redshifted
[CII] (158 um) emission from bright galaxies at
z \sim 1.2, addressing early-epoch star formation.